Three-axis inspection probe

ABSTRACT

An inspection probe capable of accurate output in three axes, having a spherical probe tip affixed to an arm. Medially disposed about the arm between the end of the spherical tip and the opposite end of the arm is a pivot ball permitting the arm to pivot at its midpoint within a housing provided. The arm passes through the spherical ball permitting additionally linear movement relative to the pivot ball. Adjoining the end of the pivot arm is a transfer pin restricted to solely linear motion. The end of the probe arm and the adjacent surface of the transfer pin are provided with adjoining sliding surfaces so that all movement of the probe tip is thus transferred into linear movement of the transfer pin in a ratio of 1:1. The transfer pin in turn effects a suitable gauge for reading the movement of the probe tip.

llnited States Patent limmerman 1 51 May 9, 1972 s41 THREE-AXISINSPECTION PROBE 2,911,727 11/1959 Steinhart ..33/l69 c [72] Inventor:Harry M Zimmerman, Roseville, Calif. [73] Assignee: Aerojet-GeneralCorporation, El Monte,

C lif FOREIGN PATENTS 0R APPLICATIONS [22] Filed; 17, 9 9 l,l84,9721/1965 Germany ..33/l72 B PP 813,852 Primary Examiner-Harry N. Haroian IRem! us. pp Dam Sgsmey-Edward O. Ansell, D. Gordon Angus and Taylor M.

[63] Continuation of Ser. No. 680,841, Nov. 6, 1967, abandoned. [57]ABSTRACT An inspection probe capable of accurate output in three axes,having a Spherical probe p amxed m an amt Mediauy [58 ne'ld 172 [74disposed about the arm between the end of the spherical tip and theopposite end of the arm is a pivot ball permitting the arm to pivot atits midpoint within a housing provided. The [56] References Chad armpasses through the spherical ball permitting additionally UMTED STATESPATENTS linear movement relative to the pivot ball. Adjoining the end ofthe pivot arm is a transfer pin restricted to solely linear mo-1,141,396 6/l915 JuPmVme "3 C tion. The end of the probe arm and theadjacent surface of the 2,090,178 8/1937 f "200/6142 transfer pin areprovided with adjoining sliding surfaces so 2,090,495 8/ 1937 8 "33/172that all movement of the probe tip is thus transferred into 212313052/1941 Frfmas 33/172 B linear movement of the transfer pin in a ratio of1:1. The 213211443 6/1943 wmdfeldtm "33/172 transfer pin in turnefi'ects a suitable gauge for reading the 2,437,190 3/1948 Gale ..33/l69movement fth Probe tip. 2,439,565 4/1948 Egor 33/172 B 2,576,590 11/1951 Gentzhorn ..33/l72 E 6 Claims, 6 Drawing Figures PKTENT'EDMAY 9I972 SHEET 1 OF 2 HARRY M. ZIMMERMAN BY W9M ATTORNEYS PATENTEBMM 9 I9123. 660,906

SHEET 2 [IF 2 FIG. 5

INVLIN'"! R HARRY M. Z IMMERMAN ATTORNEYS THREE-AXIS INSPECTION PROBEThis is a continuation of 680,841 filed 11-6-67, now abandoned.

Prior to the herein invention, many devices have existed to obtain areading of the variation in the surface of a work piece. Some of thesedevices were even able to obtain measurements along three axes, that is,an axis parallel to the axis of the device itself, and the two axesnormal thereto. It is generally desirable in such measuring devices tobe able to continually obtain measurements in planes that pass throughthe various axes on a continuous basis. Most of the prior art devices,however, are unable to continuously or simultaneously obtainmeasurements passing from one plane or axis to another without changingsettings and the like. Devices that do exist for obtaining continuousreadings along all three axes require complicated cam arrangements tocompensate for the movement according to the axis or plane in which thereading is being taken, are relatively complex in construction, and havevarious inherent limitations on the size of the overall device.Additionally, these prior art devices do not provide an output that isreadily adaptable to either a mechanical gauge reading or,alternatively, ty in the prior art devices which, like the one describedherein, convert all angular motion into linear functions, is becausethey do not so convert the movement of the probe tip into linearmotionin a 1:1 ratio so that the linear motion will always be an exactreflection of the distance traveled by the tip of the probe. Because oflacking a 1:1 conversion ratio, the prior art devices have of necessitybecome complex to compensate therefor.

Thus, it is an object of this invention to provide a three-axis probemeasuring device which reflects in a linear motion the exactdisplacement of the probe tip through any axis or plane in which the tipmoves.

A further object of this invention is to provide a three-axis probemeasuring device which has a linear output and is simple inconstruction, alleviating the requirement for cam devices to providesuch an output.

The above and other objects of this invention are accomplished by adevice comprised of an elongated housing in which is partially disposeda probe arm with one half of the arm extending from the housing andhaving a spherical tip thereon for sensing the work piece. The probe armslidably engages a rotating ball joint which is seated in the forwardend of the housing. The arm extends through the ball joint to a pointmedially disposed within the housing. The end of the probe arm withinthe housing has an inwardly tapered conical configuration which is incontact with a conically shaped end of a transversely slidable pin whichis spring loaded within the housing. The configuration of cone on thetip of the pin is approximately a 90 degree right angle cone, and as aresult, any movement relative to the end of the probe arm relative tothe pin 's conical surface will result, as will be further explained, ina precise 121 linear motion of the pin to the movement of the probe tip.Alternatively, the end of the probe arm can be conically tapered towarda receptacle cone in the pin. The opposite end of the pin can bedirectly connected in one embodiment to a differential transformer so asto obtain an electronic output. Alternatively, the pin may be connectedto a follower block which will move in accordance with the pin action.In turn, the block movement is sensed by a mechanical sensing device togive a readout on a dial that can be integral with the probe apparatus.

The operational environment for this invention is an inspection devicewhich may be utilized to measure variations in the surface contour of aworkpiece or to inspect linear measurements of products, for example, asan inspection tool in conjunction with a commercially availablethree-axis numerically controlled inspection machine. In addition, thisinvention may be used to set up work pieces in various machines, forexample, to properly position work pieces in boring machines, lathes,shapers, planers, or milling machines. When using this invention,surfaces may be probed along any axis without resetting the device as iscommonly required with existing probe devices.

electronic indication. Much of the complexi- It is believed theinvention will be better understood from the following detaileddescription and drawings in which:

FIG. 1 is an overall pictorial perspective representation of the probedevice of this invention.

FIG. 2 is a partially sectioned view of the probe of FIG. 1.

FIG. 3 is a partially sectioned end view taken along lines 3- 3 of FIG.2.

FIG. 4 is a partially sectioned pictorial view of an embodiment of theinvention utilizing an electronic output through a differentialtransformer.

FIG. 5 shows the relationship of the probe arm to the pin displaying theimportance of the conical shape.

FIG. 5a is an enlarged view of the relationship of the adjoiningsurfaces of the probe arm and transfer pin.

Turning now to FIGS. I and 2 which show an embodiment that displays anoutput readable on an attached dial indicator, there is seen the probedevice 11 having a cylindrically shaped housing 13. The housing 13 hasan outward flanged front end 17. Within the flanged portion is seated arotating ball 19 which is surrounded by a suitable bearing material 21of Teflon or other suitable material. A cover plate 23 secured by screws25 holds the bearing 21 in place within the flange 17, thus securing theball 19. The ball 19 is provided with a center aperture 27 through whichpasses in sliding engagement a corresponding cylindrical portion 29 ofthe probe arm 31 of the device 11. The forward end of the probe arm hasappropriately affixed thereto a spherical tip 33. The probe annadditionally is provided with an outwardly extending flange portion 35to the rear of the ball 19 which mates with a flat ridge surface 37formed on the ball. The rear of the probe arm 31 has an inwardly formedconical portion 39 which has a cone of, for example, 60 degrees.

Slidably mounted in the rear portion of housing 13 within acylindrically formed aperture 41 is transfer pin 43 which serves totransfer any motion of the probe arm 31 into linear motion. The transferpin 43 has a main elongated body 45 with an enlarged head portion 47which is in sliding engagement with aperture 41. The front of the headportion 47 is formed into a cone 49 of approximately degrees and engagesthe inwardly formed conical portion 39 on the end of the probe arm 31 ina manner which will be described hereinafter in more detail withreference to FIG. 5. In the region where the pin 43 passes through therear of the housing 13, it is surrounded by a bushing 51 of suitablematerial, such as plastic for example, which serves to maintain itscentering within the aperture 41 as well as to facilitate sliding motiontherethrough. Secured to pin 43 by screw 53 is a follower block 55 whichextends upwardly and outwardly from the end of housing 13. A lightspring 56 extends between the bushing 51 and head portion 47 of the pinwithin the aperture 41 so as to maintain contact between the pin and theprobe arm 31.

An additional elongated cylindrical housing 57 is affixed to the mainhousing 13 by bolts 59 and extends rearwardly for the purpose ofenclosing electrical components not utilized in this embodiment.Additionally, housing 57 can serve as a support where the probe can beheld by appropriate machinery. Mounted on top of the main body 13 of thedevice is a dial indicator 60 having a mounting shaft 61 which extendsthrough a rear flange portion 63 of the main body 13. A feeler arm 65contacts the follower block 55 such that any movement of the followerblock is reflected on the indicator 60. The dial indicator 60 is aconventional device well known in the art which can, for example, be adial indicator as described in Sec. 3. l 2 of Commercial'StandardCS8-5l, Gage Blanks, Fourth Edition, effective Apr. I5, 1951.

Turning now to FIG. 4 there is shown a modification of the devicewherein an electrical output can be obtained for use with either digitalor analog equipment. The construction of the probe 11 is essentially thesame except that the follower block 55 as seen in FIG. 2 is no longerutilized. In its place there is secured to the transfer pin 43 at thethreaded end 67 a non-magnetic transfer core shaft 69 which extendsrearwardly therefrom into the housing 57. Mounted on the core shaft is amagnetic core 71. Surrounding core 71 is a wound magnetic core 73. Abushing 75 surrounds the wound core 73 holding in tight slidingengagement the transformer core shaft 69 at the rear thereof. A firstadjustable screw 77 holds the bushing 75 in position relative to thehousing 57, while a second adjustable screw 79 acts as a set screwresting on the rear surface 80 of the bushing 75. By adjustment of thescrews 77 and 79, the bushing 75 together with the tight fittedtransformer wound magnet 73 can be moved laterally relative to the core71 so as to obtain any necessary adjustments. The leads 8] from thewound magnet 73 leave the device through an aperture 83 for connectionto a power source and suitable readout equipment. The readout equipmentmay be, for example, a voltmeter, a recorder or a digital displaydevice, each of which is well known to those versed in the art. A fillerblock 85 occupies the aperture 62 through which the dial indicator 60was formerly connected to the follower. The aforegoing provides adifferential transformer where linear movement of the core 71 within thewound magnet 73 provides a proportional change in the output in leads81.

Turning now particularly to FIG. 3, which is a partially sectioned rearview of the device in FIG. 2, there is seen an adjustable set screw 87which passes through rear housing 57 to engage the rearward portion 88of the main housing 13 for the probe device 11, as seen in FIG. 2. Theuse of this set screw 87 is particularly advantageous in the embodimentshown in FIG. 4 in which a differential transformer is used. Adjustmentof this set screw 87 serves to slightly move the main housing 13, asseen in FIG. 4, relative to the rear housing 57 and is thus used toachieve a centering of the rear housing 57 with the spherical tip 33.When the gauge 60, shown in FIG. 2 and FIG. 4, is utilized instead ofelectronic output, the mounting shaft 61 is held in tight engagementwith the rectangularly formed aperture 62 by means of a set screw 89which passes through portion 63 acting as a clamp about the shaft 61.

Turning now to FIGS. 5 and 5a for an explanation of the operation of thedevice, it is seen that the probe arm 31 moves about a pivot point C onaxis AA through the center of ball 19. The Figure shows the probe arm 31and associated transfer pin 43 in solid line outline in the originalnull position wherein all movement is along the 2-2 axis of the device.Alternatively, when the spherical tip 33 is displaced laterally, therear conical receptacle 39 of the probe arm 31 is tilted laterallyopposite and is shown in dotted outline form. In the configuration shownin FIG. 5, the distance from the center of the spherical tip 33 alongthe axis 8-8 to the axis AA through the center of the ball joint isequivalent to the distance of the probe arm from the axis AA to the rearend 91 along the C-C axis of the probe arm, which contacts the conicalsurface 49 of transfer pin 43. Thus, any displacement from the 2-1 axisalong the B-B axis is equivalent to a similar displacement in theopposite direction of the end 91 of the probe arm 31 relative to thetransfer pin 43. In other words, a relative movement of a ratio of l:lis provided about the AA axis or pivot point C when the spherical tip 33is displaced.

In the initial null position of the probe arm 33, the rear end 91thereof contacts the conical surface 49 of the transfer pin 43 at thepoint 93. After the arm has tilted, the contact point moves down thesurface of the cone toward the front of the transfer pin 43 to a newpoint 95, while the transfer pin 43 has moved rearwardly. In thisembodiment the incline of the conical surface 49 is a half angle of 90,or 45. As seen in FIG. 5a, where an enlarged view of the surface andpoints 93 and 95 are shown, it can be seen that the verticaldisplacement along x, a, will equal the linear displacement, b. Sincethe tangent of 45 is l, a b. It can be seen that, a, is equivalent tothe distance moved by the center of the spherical probe pin 33 from itsinitial starting position as seen in FIG. 5. Thus, since a 90 cone ischosen and the moment arms are equal about the axis AA, all verticaldisplacement of the probe pin is transferred into an equal lineardisplacement of the transfer pin 43. The same theory can be applied tosituations where the distance between axis AA and axis 8-8 is not equalto the distance between axis AA and axis C-C. For example, if theportion of the exposed probe arm, B-B to AA, was twice as long as thedistance internally of the housing, namely from AA to C-C, then theangle of the incline of the surface of the cone would be chosen toproduce a tangent of A. This is because the vertical displacement alongthe C-C axis would be /2 the movement of the tip along the 8-H axis,thus requiring a linear displacement along the 2-2 axis of twice thatmovement along the C-C axis. Thus, for example, the angle to producesuch a tangent of A would be 2634".

From the foregoing, it can be seen that any length of probe arm can bechosen with a suitable conical angle corresponding to the relativelength of the probe am on either side of the AA axis to achieve a 1:1linear motion. The importance of the 1:] motion is that all movement ofthe probe arm 31 is normally directly along the Z-Z axis when surfacesare encountered by the probe tip of less than a 45 angle. Once the angleof the surface increases to more than the 45, the probe tip then isdisplaced relative to the Z-Z axis as shown in FIG. 5, causing thecorresponding movement at the rear along the C-C axis, as explained.Thus, a transition exists in measuring any surface wherein movementeffectively along the 2-2 axis is transferred into the displacementmentioned. Since the ratio of movement is always l:l along the 2-2 axis,one does not have to be concerned with the transition from such movementalong that axis to the displacement of the tip from the axis, as long asthe ratio remains at 1:].

As can be appreciated from FIG. 5, it is to be noted that the movementof the probe arm 31 is about the axis AA passing through the center ofthe ball 19. Thus, the end of the spherical tip 33 and the end 91 of theprobe arm adjacent to conical surface both describe a slightly circularpath corresponding to a radius about the center point C of the AA axis.In other words, the displacement on the C-C axis is not truly linear butrather is slightly curved according to the radial movement indicated.Because of this slight curvature, compensation must be made in the faceof the conical surface 49 of the transfer pin 43 in order to obtain theprecisely accurate readings necessary for devices of this type.

To determine the slight curvature required on the surface of the cone49, the following mathematical steps are taken: l A desirable range ofprobe movement is determined; 2) the linear distance from AA to B-Bbetween the center of the pivot point C and the center of the sphericaltip 33 is chosen; (3) the linear distance between the center of thepivot point C and the end 91 along the ZZ axis to the C-C axis of theprobe arm 31 is chosen; and (4) a desirable radial distance from the ZZaxis to the point where the probe arm 31 contacts the cone surface 49 ina null position is established, which point has been designated as 93.This radial distance must equal or exceed the desirable range of probemovement. Knowing the distance from the probe tip 33 to the pivot pointC, the distance from pivot point C to the probe arm rear end 91, and theradial offset, one can readily determine by mathematical calculationsthe location of contact point 93 in the null position when the device isresting entirely along the Z axis, and can also determine mathematicallythe location of the point 95 when the probe arm 31 is in fulldeflection. By further mathematical calculations, one can similarlydetermine one or more points intennediate the point 93 and the point 95necessary to maintain a linear ratio of 1:] between the probe tip 33linear deflection and the slider arm 43 linear movement. Havingestablished three or more points along the curve to maintain a lzlratio, the curvature of the conical surface 49 may be mathematicallyestablished to compensate for the arcuate movement of the probe arm rearend 91. When the established curved surface is formed on a cone as theconical surface 49, it will correspond exactly to the arc described bythe probe arm rear end 91 of the probe device 11, and particularly itwill maintain the desired 1:1 ratio as the contact point 93 moves withdisplacement of the probe tip 33.

In reducing this invention to practice, it was known that the contactpoint 93 follows a circular path. Three points on the conical surfacewere chosen to maintain the M ratio of the probe tip 33 lineardisplacement to the sliding arm 43 linear movement. The three pointschosen were (I) the starting reference point or contact point 93, (2) apoint equivalent'to terminal travel at full probe arm deflection, whichpoint is designated 95, and (3) a point equivalent to midway between tthe contact point 93 and the full deflection point 95. Three pointsalong the cone surface having been established, it permitted thedetermination of the radius and the location of the center of a circlepassing through the three points. The conical surface 49 was then formedon the slider arm 43 as a segment of the calculated circle passingthrough the three predetermined points.

It is apparent that when the conical surface 49 is on the slider arm 43,the surface 49 will be slightly concave. It should be equally apparent,in view of the foregoing discussion, that the conical surface 49, ratherthan being formed on the transfer pin 43, can be formed just assuccessfully on the end of the probe arm 31. In that event, thecompensation will effect a slightly convex surface to compensate for theradial movement.

lclaim:

1. An inspection probe device comprising:

An elongated housing having a front end with an opening therein;

a ball having a diametral hole therethrough, said ball being pivotallymounted in said opening;

a probe arm having a probe tip thereon remote from said housing, saidprobe arm slidably mounted in said ball and capable of motion in threemutually perpendicular planes, said probe arm extending from said probetip outside said housing, through said ball, and terminating within saidhousing;

a transfer pin slidably disposed in said housing contacting theterminating end of said probe arm to directly transform all displacementof said probe arm to linear movement of said transfer pin in a singleplane, said end of said probe arm and the adjacent end of said transferpin being provided with conical, contacting, adjoining, slidablesurfaces to achieve a percise predetermined relationship of relativemovement of said probe arm to the resulting linear movement of saidtransfer pin, one of said conical surfaces being a protruding conicalsurface and the other of said conical surfaces being a receptacleconical surface, said protruding conical surface having a greater apexangle than said receptacle conical surface;

and means connected to said transfer pin for acting in cooperation withsuitable readout devices, wherein the contacting, adjoining slideablesurfaces of said probe arm and said transfer pin include a conicalsurface formed on one member and a suitable receptacle formed in theother, said conical surface having an arcuate curvature thereon, saidcurvature being in the conical-axial plane of revolution of said conicalsurface and extending from the apex to the base of said conical surface,said conical surface and said curvature having a predeterminedrelationship with the lengths of said probe arm, one length extendingoutwardly from a pivot point within said ball to said probe tip and theother length extending inwardly from said pivot point to the point ofcontact of said contacting surfaces, to achieve a 1:1 ratio of movementof said arm to said pin.

2. The device of claim 1 wherein said pin is provided witha concavelyarcuate, conical surface tapering toward said probe arm,

the contacting adjacent end of said probe arm being provided with areceptacle for receiving said conical surface of said pin.

3. The device of claim 1 wherein the end of said probe arm within saidhousing is provided with a convexly arcuate, conical surface taperingtoward said transfer pin,

the adjacent end of said transfer pin being provided with a receptaclefor receiving said conical surface of said probe arm.

4. An inspection probe device comprising:

an elongated housing,

a rotatable ball disposed in the forward end of said housing,

a probe arm extending outwardly from said housing through, and insliding engagement with, said ball, said arm terminating in saidhousing,

a spherical member provided on the exposed end of said probe arm outsideofsaid housing,

a transfer pin disposed in said housing adjacent the end of said probearm, said pin limited solely to linear movement,

means for maintaining continuous contact between adjoining surfaces ofsaid pin and said probe arm,

a conical-shaped surface formed on one of said adjoining surfaces, saidconical-shaped surface having an arcuate curvature thereon, saidcurvature being in the conicalaxial plane of revolution of saidconical-shaped surface and extendingfrom the apex to the base of saidconicalshaped surface, said conical-shaped surface and said our vaturehaving a predetermined relationship with the lengths of said probe am,one length extending outwardly from a pivot point within said ball tosaid spherical member and the other length extending inwardly from saidpivot point to the point of contact of said adjoining surfaces, toresult in a 1:1 ratio of movement of said probe arm to said pin,

a receptacle formed in the other of said adjoining surfaces forreceiving said conical-shaped surface,

and means connected to said pin for acting in cooperation with suitablereadout devices.

5. An inspection probe device comprising:

a probe arm having a probe tip and means for mounting said probe arm tobe universally pivotal in a fixed plane and to have linear motion withrespect to said plane;

a transfer pin in operable association with said probe arm and means formounting said transfer pin so as to be restrained to linear motionnormal to said plane;

a pair of adjacent, contacting, conical surfaces in slidable touchingrelationship intermediate said probe arm and said transfer pin, whereina protruding conical surface is received by a receptacle conicalsurface, said protruding conical surface having a greater apex anglethan said receptacle conical surface, one of said conical surfaces beingmounted on said probe arm and the other of said conical surfaces beingmounted on said transfer pin to effect the transmittal of motion fromsaid probe arm to said transfer pin in a precise predeterminedrelationship of relative motion for all displacement of said probe arm;

and means responsive to motion of said transfer pin for effectingreadout, wherein said pair of adjacent contacting conical surfacescomprises a protruding cone forming one of said surfaces, said conehaving a slightly arcuate configuration between the apex and basethereof, and a coneshaped cavity forming the other of said surfaces,said cavity constituting a receptical for receiving said protruding conewhereby any displacement of said probe arm causes said surfaces to slidein relation to each other and transmits motion to said transfer pin.

6. The device of claim 5 wherein said protruding cone has an apex angleof about degrees and said cone-shaped cavity has an apex angle of about60 degrees.

1. An inspection probe device comprising: An elongated housing having afront end with an opening therein; a ball having a diametral holetherethrough, said ball being pivotally mounted in said opening; a probearm having a probe tip thereon remote from said housing, said probe armslidably mounted in said ball and capable of motion in three mutuallyperpendicular planes, said probe arm extending from said probe tipoutside said housing, through said ball, and terminating within saidhousing; a transfer pin slidably disposed in said housing contacting theterminating end of said probe arm to directly transform all displacementof said probe arm to linear movement of said transfer pin in a singleplane, said end of said probe arm and the adjacent end of said transferpin being provided with conical, contacting, adjoining, slidablesurfaces to achieve a percise predetermined relationship of relativemovement of said probe arm to the resulting linear movement of saidtransfer pin, one of said conical surfaces being a protruding conicalsurface and the other of said conical surfaces being a receptacleconical surface, said protruding conical surface having a greater apexangle than said receptacle conical surface; and means connected to saidtransfer pin for acting in cooperation with suitable readout devices,wherein the contacting, adjoining slideable surfaces of said probe armand said transfer pin include a conical surface formed on one member anda suitable receptacle formed in the other, said conical surface havingan arcuate curvature thereon, said curvature being in the conical-axialplane of revolution of said conical surface and extending from the apexto the base of said conical surface, said conical surface and saidcurvature having a predetermined relationship with the lengths of saidprobe arm, one length extending outwardly from a pivot point within saidball to said probe tip and the other length extending inwardly from saidpivot point to the point of contact of said contacting surfaces, toachieve a 1:1 ratio of movement of said arm to said pin.
 2. The deviceof claim 1 wherein said pin is provided with a concavely arcuate,conical surface tapering toward said probe arm, the contacting adjacentend of said probe arm being provided with a receptacle for receivingsaid conical surface of said pin.
 3. The device of claim 1 wherein theend of said probe arm within said housing is provided with a convexlyarcuate, conical surface tapering toward said transfer pin, the adjacentend of said transfer pin being provided with a receptacle for receivingsaid conical surface of said probe arm.
 4. An inspection probe devicecomprising: an elongated housing, a rotatable ball disposed in theforward end of said housing, a probe arm extending outwardly from saidhousing through, and in sliding engagement with, said ball, said armterminating in said housing, a spherical member provided on the exposedend of said probe arm outside of said housing, a transfer pin disposedin said housing adjacent the end of said probe arm, said pin limitedsolely to linear movement, means for maintaining conTinuous contactbetween adjoining surfaces of said pin and said probe arm, aconical-shaped surface formed on one of said adjoining surfaces, saidconical-shaped surface having an arcuate curvature thereon, saidcurvature being in the conical-axial plane of revolution of saidconical-shaped surface and extending from the apex to the base of saidconical-shaped surface, said conical-shaped surface and said curvaturehaving a predetermined relationship with the lengths of said probe arm,one length extending outwardly from a pivot point within said ball tosaid spherical member and the other length extending inwardly from saidpivot point to the point of contact of said adjoining surfaces, toresult in a 1:1 ratio of movement of said probe arm to said pin, areceptacle formed in the other of said adjoining surfaces for receivingsaid conical-shaped surface, and means connected to said pin for actingin cooperation with suitable readout devices.
 5. An inspection probedevice comprising: a probe arm having a probe tip and means for mountingsaid probe arm to be universally pivotal in a fixed plane and to havelinear motion with respect to said plane; a transfer pin in operableassociation with said probe arm and means for mounting said transfer pinso as to be restrained to linear motion normal to said plane; a pair ofadjacent, contacting, conical surfaces in slidable touching relationshipintermediate said probe arm and said transfer pin, wherein a protrudingconical surface is received by a receptacle conical surface, saidprotruding conical surface having a greater apex angle than saidreceptacle conical surface, one of said conical surfaces being mountedon said probe arm and the other of said conical surfaces being mountedon said transfer pin to effect the transmittal of motion from said probearm to said transfer pin in a precise predetermined relationship ofrelative motion for all displacement of said probe arm; and meansresponsive to motion of said transfer pin for effecting readout, whereinsaid pair of adjacent contacting conical surfaces comprises a protrudingcone forming one of said surfaces, said cone having a slightly arcuateconfiguration between the apex and base thereof, and a cone-shapedcavity forming the other of said surfaces, said cavity constituting areceptical for receiving said protruding cone whereby any displacementof said probe arm causes said surfaces to slide in relation to eachother and transmits motion to said transfer pin.
 6. The device of claim5 wherein said protruding cone has an apex angle of about 90 degrees andsaid cone-shaped cavity has an apex angle of about 60 degrees.